How Insensitive
Antonio-Carlos Jobim
Bossa NovaD-4/4
48
chords
14
different scales
8
tonal centres
First bars
DmDmC#dim7C#dim7
The harmony descends in a straight line, and it's that line that makes everyone play one scale from beginning to end. There are forty-eight chords and eight tonal centres — it isn't one scale.
The third bar brings a diminished chord, and there are four of them in the tune. The diminished is the chord that most divides opinion among people who study improvisation, because there are genuinely different readings for it and each one changes the mood of the whole phrase.